Current impulse transmitter



Oct. 20, 1964 H. SAUER ETAL CURRENT IMPULSE TRANSMITTER 2 Sheets-Sheet 1Filed Aug. 10, 1962 W/LL/ WEBER R max m H 6 V v/ mN Mw A 4 g F 3 F gAttorneys TRANSMITTER n 2 3 5 iv United States Patent 3,153,704 C NTIMPULSE TRANSMITTER Hans Sauer, Hauptstrasse 97, Volkertshausen,Aachtal, Singen, Hoilentwiel, Baden, Germany; August Gaiser,Ehingerstrasse 66, Aach, Hogan, Singen, Hohentwiel, Baden, Germany; andWilli Weber, Borrisriedstrasse 6, Volkertshausen, Aachtal, Singen,Hohentwiel, Baden, Germany Filed Aug. 10, 1962, Ser. No. 216,137 Claimspriority, application Germany Feb. 20, 1962 Claims. (Cl. 179-90) Theinvention relates to a pulsing device for (telephone installations,which device is accommodated in one housing.

The purpose of the invention is to ensure reliable actuation of and verysafe operation of such a pulsing device of low production cost.

A pulsing device for telephone installations is known which is operatedby interchangeable cams which are longitudinally non-displaceable andcan be rotated mechanically by means of a power drive. The controlcombinations in any given case are set on the cams.

Associated with the cams are a common locking pawl and individualmovable follower member each serving to follow one cam. Before eachselection process the followers are moved manually from their restposition to their operating position. The followers remain in theoperating position for the duration of the selection process,automatically connect the power drive for the cams, and disconnect theapparatus again, returning the elements which were moved to theirinitial state, when a person has been selected by transmitting thedesired number-combination by operation of a key. In the operating statethe followers are in range both of the corresponding cam and of thelocking pawl. On the cam there are the impulse-combinations representinga desired telephone number. In its operating position, the followerwhich has been moved by pressing the associated key is then locatedbetween the cam and-the locking pawl so that the telephone number,represented by raised and recessed portions on the cam, moves thelocking pawl. In the known construction a short-circuiting contact wasthen operated in synchronism with this movement of the locking pawl.

The short-circuiting contact operated transmitted the impulses to thetelephone network. The movement of the contact had to be a true image ofthe combination of raised and recessed portions on the cam, for thedesired telephone number, made up of current impulses, to be transmittedundistorted. Wrong connections could be made, for example if the currentwas cut off while the cams were operating, or if some members were madeinaccurately and thereby contacts were not opened or closed at thecorrect time. It was also diflicult to exchange the cams, and this couldalso cause wrong connections.

The invention aims to avoid these disadvantages and to construct thepulsing device so that it can be manufactured with comparatively littleprecision, for example by stamping the individual members, and yet has ahigh degree of accuracy in transmitting series of impulses, is veryreliable in operation and makes wrong connections extremely improbableif not impossible.

According to the invention, the moved locking pawl, acting through aclutch, drives an impulse and a looking wheel and thus operates theimpulsing send and interval contacts.

In this construction, a short-circuiting contact is no longer operateddirectly or indirectly through levers, but through the medium of aclutch. The clutch, which has 3,153,704 Patented Oct. 20, 1964 animpulse and a locking wheel, ensures that series of impulses aretransmitted accurately, even if the locking pawl does not move veryaccurately due to lack of precision in manufacture.

It is desirable for the clutch to be a slipping clutch which is drivenby the drive for the cam and is locked by an impulse pawl which engagesin the locking wheel and which simultaneously closes the send contactwhen the locking pawl causes the locking wheel to be released.

It is sufficient for the locking pawl to actuate a clutch. The clutchthen ensures that, by operating the appropriate send and intervalcontacts, an impulse is followed by the correct interval by aninterruption of the loop. Thus the pawl is now used only to release theclutch and no longer has the function of transmitting both the sendimpulse and the interval in the correct relative rhythm.

It is desirable for the clutch to be released by means of angle leverswhich are connected to the locking pawl through levers. The clutchitself is constructed with the locking and the impulse wheel mountedagainst relative rotation on a hollow bush with a friction surface, thehollow bush being mounted on the driving shaft and resiliently urgedagainst the friction surface which is fixed to the latter.

The locking and the impulse wheel operate the send and the intervalcontact respectively. An impulse pawl drops into the locking wheel whichis simultaneously operating the send contact, so that at an exactlydefined point of time when the locking pawl makes the impulse pawl move,the send and interval contacts are successively closed at the correcttiming sequence, the sequence of send impulses and intervals is now asaccurate as if interruption were effected directly from a dial. Asstated above, the movement of the locking pawl no longer needs toinitiate exactly the interval of time between the impulses and theinterruptions, since it is only responsible for starting and stoppingthe clutch after each impulse. Any errors which may arise due toinaccuracy in manufacture thus make themselves felt only during a shortpartial movement of the clutch, and when the next movement is maderelease is once more accurate. With the known construction, all theerrors made while a cam is running are summated. Such a cam,whichaccording to the numbers selectedsometimes had to transmit todiiferent impulses, had to be manufactured with great precision, andalso all the movements from the start through the cam to the stoppingprocess and the transference of movement to the locking pawl and shortcircuiting contact had to be made with so little play that any practicalapplications of such a pulsing device was impossible, since productioncosts were much too high, or else in the course of time wrongconnections were inevitable due to inevitable inaccuracy, slackness, theaction of heat, etc.

The driving shaft for the clutch is preferably connected to the drivefor the cams by a worm drive.

The impulse wheel and the locking wheel are preferably each providedwith three recesses offset by which alternately open the intervalcontact when the send contact is closed and vice versa.

It is also important for the recesses in the locking wheel to haverising surfaces for operating the send contact and sharply steppedsurfaces to prevent the locking wheel from rotating after the impulsepawl has dropped in.

Owing to the construction of the impulse and the looking wheel, thestarting position defined, which is arrived at following appropriateoperation by the locking pawl after the impulse pawl has dropped,enables the locking wheel, so to speak, to run always from zero withoutallowing any errors to be summated, as stated above. Since there arethree cams offset by 120, the path corresponding to the 120 is availableto compensate for any errors. It is a simple matter to use suitablereductions or possibly more or less cams in order to gain still moretime to compensate for errors occurring when the movement is transferredfrom the raised and recessed portions of the cam until the clutch isreleased.

Operating safety is increased if a stop lever, which is moved in knownmanner by the follower and allows the cam to rotate, has a pawl at theend facing the follower, which pawl positively engages the follower andis in the region of the switch for the drive, the switch being attachedto one end of an angle lever of which the other end is acted upon by aswitching cam connected to the control cams.

This construction makes use of a switch with a movable operating lug.The effect of this is that whenever it is at all possible to operate theswitch the apparatus is ready for use. If the operating lug is outsiderange of the pawl, the switch cannot be operated. By simply adjustingthis conveniently designed microor snap-switch great operating safetycan be obtained with simple means.

In order to cut out the noise made by the followers following the camsbut not in the operating position, a lifting disc can be providedcoaxially with the control and switching cams, the lifting disc having acam which is followed by the roller of a lever and which, through alifting pawl, raises those followers which are not involved in theselection process out of range of the locking pawl and earns.

In order to. prevent the apparatus from continuing to operate if thecurrent is suddenly cut off, it is desirable for the switch for thedrive also to operate a magnet of which the armature carries a stop pawlwhich, when the armature is attracted, engages in known manner behind aneb of the follower when the latter is in the operating position.

In this construction the followers are thus arrestedelectromagnetically, so that any current failure or any changes in thecircuit necessarily return the apparatus to the rest position andsimultaneously disconnect it, so that normal telephone operation cannotbe disturbed.

The keys moving the followers preferably have U- shaped recesses whichengage projections from the followers.

This construction prevents excess lost motion, since the positiveconnection given by the keys moves the followers more surely.

Another essential for reliable operation is that the cams can easily beexchanged even by a layman without the operating efiiciency of theapparatus suffering. The cams are changed if the keys are to selectdifferent telephone numbers. There are various possible methods of doingthis.

It is desirable, however, for the cams to have a main radial slot with agroove in one side, the groove being arcuate and serving to receive arotary locking shaft having a flat.

In known constructions resilient elements were inserted, which requireda certain dexterity to operate and move and were also quite expensive toproduce. The cams are placed on the shaft by means of flattened portionsprovided on the latter to cooperate with the main slot.

In this way the cams are fixed against rotation on the shaft whichcauses the cams to be driven and rotated.

The locking shaft has a slot which acts as a keyhole for a key turningthe shaft.

The rotation of the locking shaft towards the free or closed position.is limited by a spring roller mounted on one side of the shaft with anabutting segment, so that secure fastening of the cam is ensured in allcases.

The keyhole is preferably covered by a plate pivoted by gravity, so thatthe key and stopping pin can be inserted only when the apparatus is in aspecific position.

The purpose of such a construction is to make it impossible to removecams when they cannot drop out by their own gravity. It is alsoimpossible to start up the apparatus when the key is still inserted,since an appropriate stopping pin prevents this.

A further operating safeguard consists in providing a send and a relaycontact actuated by the handset cradle in the circuit of the magnet andthe motor switch respectively to allow the cams to be driven only whenthe handset has been raised.

It is impossible to operate the apparatus if the handset is not raised.In the known construction, one could operate it beforehand and had toaccept the fact that impulses were transmitted which did not becomeeffective in the telephone network. Incorrect number selection was thusinevitable.

Examples of the invention are illustrated in the accompanying drawingwhich, together with the related description, contains further featuresof the invention. In the drawings:

FIG. 1 is a diagrammatic view of a cam with the support member in therest position and with the clutch through which the impulses aretransmitted;

FIG. 2 is a diagrammatic front elevation of the clutch with thecorresponding working and rest contacts for transmitting series ofimpulses;

FIG. 3 is a side elevation of a section along the line FF in FIG. 2;

FIG. 4 is a section along the line GG in FIG. 2;

FIG. 5 is a diagrammatic View of the control roller with the lockingshaft at the side from which the latter is turned;

FIG. 6 is a side elevation of FIG. 5 along the line AA;

FIG. 7 is a section along the line B-B in FIG. 5;

FIG. 8 is a section along the line C-C in FIG. 5;

FIG. 9 is a section along the line DD in FIG. 5;

FIG. 10 is a section along the line E--E in FIG. 5, and

FIG. 11 shows a stamped cam with raised and lowered portions fortransmitting series of impulses.

The housing and the keys mounted therein are constructed as described inGerman Patent No. 1,034,218.

FIG. 1 shows the control shaft 1, which carries with it a cam 2 in thedirection of the arrow 3 without relative rotation. The cam, as showninv FIG. 11, has raised portions 4 and recesses 5 which determine theimpulsesequence of the impulses and of the numbers dialled. The cam 2 ismonitored by a cam follower member 6 when the latter is in the operatingcondition. In the position shown, movement of the follower in thedirection of the arrow 7 would bring the projection 8 of the followerinto a groove 9 in a locking pawl 10 but would not move the lockingpawl. Thus the neb 11 of the follower, which neb is reciprocated bysuccessive contact with the raised portions 4 and recesses 5, does notproduce any movement of the locking pawl. According to how many keys areprovided and how many selectable numbers the apparatus contains, thecams 2 and followers 6, together with the corresponding number of keys,are arranged one behind the other perpendicularly to the plane of FIG. 1at a spacing such as is shown, for example, in FIG. 5. A lifting camdisc 12 and switching disc 13, to be described below, are howeverassociated with all the followers in common. When the key 14 isdepressed in the direction of the arrow 15, then its U-shaped recess 16entrains the projection 17 on the follower 6 and thus moves the latterin the direction of the arrow 18. The follower is, in known manner,guided for linear motion by a guide groove 19, in which a guide member20- is mounted. At the side facing the carn, the follower has a neb 21,a recess 22 and a neb 23. A spring 24 endeavours to draw the follower 6in the opposite direction to the arrow 18. When it moves in thedirection of the. arrow 18, however, the recess 22, which is positivelyengaged by a pawl 25, pivots the latter about its fulcrum. 26 in thedirection of the arrow 27, so that it operates the actuating pin 28 ofthe motor and magnet switch 29. This switch connects the drive (notshown) for the shaft 1 and also the magnet 30, the armature 31 of whichpivots the stop pawl 32 about its fulcrum 33 so that it comes to restbehind the neb 23. The follower 6 is thus arrested in its operatingposition. Unlocking is effected electromagnetically, i.e. when thecurrent has been cut off, both the spring 44 for the magnet and themotor-magnet switch immediately bring these elements out of the range ofaction of their actuating members and enable the follower 6 to springback into the rest position.

As soon as the shaft 1 and cam 2 have completed a revolution in thedirection of the arrow 3, the neb of the disc 13 (shown at the top ofFIG. 1) pivots a large angle lever, to the other end of which the motorand magnet switch 253 is fixed. This brings the switch out of the rangeof the switching pawl 25. The switch 29 therefore opens and cuts oif theenergisation of the electromagnet 36. The follower 6 is now freed andmoves opposite to the direction of the arrow 18. At the same time aspring 47 pivots the check lever 46, since the pawl turns anticlockwise.This brings the projection 48 into contact with the recess 49 in thedisc 13. The system which is movable as a unit is thus arrested again inthe correct starting position for the next switching step.

When the pawl 25 switches on the switch 29 by means of the check lever46, it simultaneously causes the latter to pivot its projection 48 outof the recess 49 in the disc 13 under the force of the spring 47. Thisensures that the disc 13 and thus the roller 1 cannot move until thedrive for the shaft has been switched on. It is desirable also to mounta slipping clutch between the shaft and the drive, in order to make thecam 2 immediately start turning at a uniform speed, thus ensuring thatthe impulses are transmitted accurately and any fluctuations in thestarting conditions of the drive cannot aifect the accuracy of thearrangement.

When the shaft 1 moves in the direction of the arrow 3, the lifting camdisc 12 also rotates and, when an associated follower roller 56 hasmoved up to the surface 51 on the disc 12, the lifting pawl 52 thenpivots about its fulcrum 53, thus bringing all the followers 6 to reston the pawl 52, together with their cams, out of range of the raisedportions 4 of the cam 2. However, if the follower 6 has been moved inthe direction of the arrow 18, its recess 21 drops behind the liftingpawl 52, so that the neb it simultaneously passes into range of theraised and recessed portions of the cam 2 and its projection 8 movesunder the projection 54 of the locking pawl 16. The neb 11 andprojections 8 and 54, which are now reciprocating in the direction ofthe arrow 7, make the locking pawl 16 pivot about its axis of rotation55 in synchronism with these movements. The reciprocating movement istransferred by a lever 56, pivoting about its fulcrum 57, to the anglelever 58, pivoting about its fulcrum 59, thus also moving the anglelever 60, which bears on the lever 58 and pivots about its fulcrum 61.It will be appreciated that the movement of the locking pawl it) can beenlarged by an appropriate choice of these levers or of other knowntypes of lever systems. The angle lever 60 then moves the impulse pawl62, which is in the form of a lever, about its fulcrum 63 against thetension of the spring 64. As shown in FIGS. 2 and 3, one end of theimpulse pawl 62 bears on a sharply stepped surface 66 of the lockingwheel 67. If the impulse pawl or the end is moved in the direction ofthe arrow 68 (FIG. 3), then the clutch 69 (shown in its entirety in FIG.2) can operate, since it is constantly driven through a worm drive 76 bythe drive for the shaft 1. Under the action of the spring 73, thedriving shaft 71 urges a friction disc 72, which is fixed to the shaft71, towards a friction disc (not shown) fixed on the hollow bush 74. Thelocking wheel 67 and impulse wheel 75 are mounted on the hollow bushagainst relative rotation. When the end 65 of the impulse pawl 62 movesin the direction of the arrow 68, both the locking wheel 67 and theimpulse 6 wheel 75 rotate in the same direction as the driving shaft 71.

Both the locking wheel and the impulse wheel have recesses which areoffset by 120. In the locking wheel rising surfaces 77 adjoin sharplystepped surfaces 66, forming lugs, while the impulse wheel hasprojections 73 which are stepped on both sides.

Movement of the impulse pawl 62 in the direction of the arrow 68simultaneously closes a contact 79, which is inserted in the line to theexchange, as known in telephone technique. This contact, which is nowacting as a working contact and forming the irnpulsing loop, is theninterrupted by a contact 80 also in the exchange line acting as aninterval contact. Alternate operation of the contacts produce thedesired series of impulses.

Manufacturing inaccuracy is compensated for, in that it is importantonly, for example, for the work contact to be closed at some time whilethe interval contacts are opened an interposed projection 78, thuscausing a circuit-break. The work contact must then become active at arange offset by 120 after the interval contact has closed. Thisconsiderably simplifies production, since the locking pawl 11 is usedonly to release the clutch 69 and any inaccuracy in the transference ofimpulses is compensated for by the enforced neutral position when theimpulse pawl 62 locks the locking wheel 67.

Possible constructions to make it easy to change the cams are shown inFIGS. 5 to 11. These consist in providing the shaft 1 with flattenedportions 81, 82 (FIG. 10) so that a guide member 83 is adapted forinsertion in a main slot 84 of the cam 2. The main slot has an arcuategroove 85 which is engaged by a locking shaft 86 when it is turned intothe position shown in FIG. 8. If the locking shaft 86 is turned by thekey 87 far enough in the direction of the arrow 88 (FIG. 8) for thestraight surface 89 to be aligned with the main slot 84, then the cam 2can be drawn out in the direction of the arrow 96 without any trouble.Correct positioning of the locking shaft 86 both when it is locked, asshown in FIG. 8, and when it is released, is obtained by means of aspring roller 91, which is pressed by an annular spring 2 against anabutting extension 93 attached to the locking shaft 86. This ensuresdefinite engagement in one or other position.

In order to ensure that the cam 2 can only be removed when the apparatusis turned upside down the projection 94 on the locking shaft 86, whichis engaged by the slot 95 of the key 87, is covered by a cover plate 96.A keyhole 97 in the cover plate has a slot 98 which is adapted tocooperate with the arresting pin 99 of the key. When the key is inposition the pin 99 can rotate the extension 93. Also provided on thehousing is a flap 100 which pivots by gravity about its fulcrum 101. Inthe position shown in FIG. 6 it is impossible to insert the key 87,since the flap 1% covers the keyhole 97. If the apparatus is tilted, forexample, in the direction of the arrow 162, then the flap 100 eventuallyexposes the keyhole, since the cover plate 96 now changes its positionin relation to the flap 100.

This means that the cams 2 can be changed only in a specific operatingposition. If the apparatus is returned to the normal position withoutthe key being pulled out, then the key cannot be removed, so that in anyevent the apparatus is ready to operate only if the members are in theirstructurally correct position. Only when the apparatus is mounted readyto operate does the flap 100 drop back into a position where it exposesthe slot 98, and the arresting pin 9 can then be pulled out through theslot.

The invention can be applied to all cases where a pulsing device, readyto operate and functioning efficiently, is to be made with lowproduction costs and little expenditure on adjustment.

What we claim is:

1. Pulse transmitter for telephones comprising: at

least two rotatable cams; a follower member for each of said cams,normally kept out of the range of its respective associated cam; acommon locking pawl actuated by said follower members in synchronismwith cam action thereupon; a key associated with each of said followermembers for selectively placing such associated follower member in theactuating ranges of its associated cam and of said locking pawl; meansactuated in synchronism with selection of a follower member forretaining said follower member after selection thereof in said actuatingranges of said cam and of said locking pawl; means actuated insynchronism with said cams for removing said selected follower memberfrom said actuating ranges; a rotatable pulse wheel; a first contactactuated by said pulse wheel; a rotatable locking wheel; a secondcontact actuated by said locking wheel; driving means; and meansoperated by said locking wheel for simultaneously connecting saidlocking wheel and said pulse wheel to said driving means.

2. Transmitter as set forth in claim 1, said keys being angle levershaving a U-shaped recess receiving a projection of its associatedfollower member for engagement therewith.

3. Pulse transmitter for telephones comprising: at least two rotatablecams; means for driving said cams; a follower member for each of saidcam-s, normally kept out of the range of its respective associated cam;a common locking pawl actuated by said follower members in synchronismwith cam action thereupon; a key associated and engaged with each ofsaid follower members for selectively placing said associated followermembers in the actuating ranges of its associated cam and of saidlocking pawl; means actuated in synchronism with selection of a followermember for retaining said follower member after selection thereof insaid actuating ranges of said cam and of said locking pawl; meansactuated in synchronism with said cams for removing said selectedfollower member from said actuating ranges; a pulse wheel and a lockingwheel mounted for rotation in unison; means for disengageably, drivinglyconnecting said two wheels to said driving means; contact meansindividually actuated by said wheel; and a pawl linked to said lockingpawl and engaging and disengaging said locking wheel in synchronism withactuation of said locking pawl so as to govern engagement of said wheelsto said driving means.

4. Pulse transmitter for telephones comprising: at least two rotatablecams; means for driving said cams; a follower member for each of saidcams, normally kept out of the range of its respective associated cam; acommon locking pawl actuated by said follower members in synchronismwith cam action thereupon; a key engaged with each of said followermembers for selectively placing said engaged follower member into theactuating ranges of its associated cam and of said locking pawl; meansactuated in synchronism with selection of said follower member forretaining said follower member after selection thereof in said actuatingranges of said cam and of said locking pawl; means actuated insynchronism with said cams for removing said selected follower memberfrom said actuating ranges; a pulse wheel and a locking wheel mountedfor rotation in unison; means for disengageably, drivingly connectingsaid two wheels to said driving means; contact means individuallyactuated by said wheels; a double arm lever having one arm selectivelyengaging and disengaging said locking wheel so as to govern engagementof said wheels with said driving means; and linkage means including atleast one angle-lever for linking said locking pawl to the other arm ofsaid double arm lever for actuation thereof in synchronism withactuation of said locking pawl.

5. Pulse transmitter for telephones comprising: at least two rotatablecams; means for driving said cams; a follower member for each of saidcams, normally kept out of the range of its respective associated cam; acommon locking pawl actuated by said follower members in synchronismwith cam action thereupon; a key engaged with each of said followermembers for selectively placing said engaged follower member into theactuating ranges of its associated cam and of said locking pawl; meansactuated in synchronism with selection of a follower memher forretaining said follower member after selection thereof in said actuatingranges of said cam and of said locking pawl; means actuated insynchronism with said cams for removing said selected follower memberfrom said actuating ranges; a pulse wheel and a locking wheel mounted ona hollow shaft; a second shaft receiving said hollow shaft and beinggeared to said driving means, there being means including spring andfriction means for drivingly engaging said hollow shaft with said secondshaft; contact means individually actuated by said wheels; and meanslinked to said locking pawl and engaging and disengaging said lockingwheel in synchronism with actuation of said locking pawl so as to governengagement of said two shafts.

6. Transmitter as set forth in claim 5, said second shaft being gearedto said driving means by a worm gear.

7. Transmitter as set forth in claim 5, said wheels each are providedwith recesses offset by whereby each wheel opens its associated contactmeans when the other wheel closes its associated contact means.

8. Pulse transmitter for telephones comprising: at least two rotatablecams; means for driving said cams; a follower member for each of saidcams, normally kept out of the range of its respective associated cam; acommon locking pawl actuated by said follower members in synchronismwith cam action thereupon; a key engaged with each of said followermembers for selectively placing said engaged follower member into theactuating ranges of its associated cam and of said locking pawl; meansactuated in synchronism with selection of a follower memher forretaining said follower member after selection thereof, in saidactuating ranges of said cam and of said locking pawl; means actuated insynchronism with said cams for removing said selected follower memberfrom said actuating ranges; a locking wheel having gradually sloping camsurfaces respectively succeeded along the circumference thereof bysharply dropping flanks; a pulse wheel connected to said locking wheeland mounted for rotation in unison therewith; means for drivinglyengaging said driving means with said two wheels; contact meansindividually actuated by said wheels; and means linked to said lockingpawl and scanning said cam surfaces and flanks of said locking wheel soas to govern engagement of said two wheels with said driving means insynchronism with actuation of said locking pawl.

9. Pulse transmitter for telephones comprising: at least two rotatablecams; means for driving said cams; a follower member for each of saidcams, normally kept out of the range of its respective associated cam; acommon locking pawl actuated by said follower members in synchronismwith cam action thereupon; a key engaged with each of said followermembers for selectively placing said engaged follower members into theactuating ranges of its associated cam and of said locking pawl; meansactuated in synchronism with selection of a follower member forretaining said follower member after selection thereof in said actuatingranges of said cam and of said locking pawl; a stop lever for arrestingany of said cams in a preselected position and being engageable withsaid selected follower member for moving out of the arresting position;switch means governing said driving means and being actuated by saidstop lever; means actuated in synchronism with the rotation of said camsfor removing said selected follower member from said actuating ranges ofsaid cam and of said locking pawl thereby causing said stop lever to beplaced into its arresting position; a rotatable pulse wheel; a firstcontact actuated by said pulse wheel; a rotatable locking wheel; asecond contact actuated by said locking wheel; and means operated bysaid locking pawl for simultaneously connecting said locking wheel andsaid pulse wheel to said driving means.

10. Pulse transmitter for telephones comprising: at least two rotatablecams; means for driving said earns; a follower member for each of saidcams, normally kept out of the range of its respective associated cam; acommon locking pawl actuated by said follower members in synchronismwith cam action thereupon; a key engaged with each of said followermembers for selectively placing said engaged follower member into theactuating ranges of its associated cam and of said locking pawl; meansincluding a lifting disc rotating with said cams and further including alifting pawl actuated by said disc for placing any non-selected followermember out of the ranges of its associated cam and of said locking pawlupon rotation of said cams; means actuated in synchronism with selectionof a follower member for retaining said follower member after selectionthereof in said actuating ranges of said cam and of said locking pawl;means actuated in synchronism with said cams for removing said selectedfollower member from said actuating ranges of said cam and of saidlocking pawl; a rotatable pulse wheel; a first contact actuated by saidpulse wheel; a rotatable locking wheel; a second contact actuated bysaid locking wheel; and means operated by said locking pawl forsimultaneously connecting said locking wheel and said pulse wheel tosaid driving means.

11. Pulse transmitter for telephones comprising: at least two rotatablecams; means for driving said cams; a follower member for each of saidcams, normally kept out of the range of its respective associated cam; acommon locking pawl actuated by said follower members in synchronismwith cam action thereupon; a key engaged with each of said followermembers for selectively placing said engaged follower member into theactuating ranges of its associated cam and of said locking pawl; magnetmeans for retaining said selected follower member in said ranges; switchmeans governing said driving means and said magnet means and beingactuated by said selected follower member; means actuated in synchronismwith said cams for removing said selected follower member from saidactuating ranges of said cam and of said locking pawl; a rotatable pulsewheel; a first contact actuated by said pulse wheel; a rotatable lockingwheel;

10 a second contact actuated by said locking wheel; and means operatedby said locking pawl for simultaneously connecting said locking wheeland said pulse wheel to said driving means.

12. Pulse transmitter for telephones comprising: a main shaft; means fordriving said shaft; at least two cams, each having a slot for mountingon said shaft, each slot having an arcuate groove; a locking shaftextending parallel to said main shaft, projecting through said slots andlocking said cams to said main shaft when projecting into said arcuatedgroove; a follower member for each of said cams, normally kept out ofthe range of its respective associated cam; a common locking pawlactuated by said follower members in synchronism with cam actionthereupon; a key engaged with each of said follower members forselectively placing said engaged follower member into the actuatingranges of its associated cam and of said locking pawl; means actuated insynchronism with selection of a follower member for retaining saidfollower member after selection thereof in said actuating ranges of saidcam and of said locking pawl; means actuated in synchronism with saidcams for removing said selected follower member from said actuatingranges; a rotatable pulse wheel; a first contact actuated by said pulsewheel; a rotatable locking wheel; a second contact actuated by saidlocking wheel; and means operated by said locking pawl forsimultaneously connecting said locking wheel and said pulse wheel tosaid driving means.

13. A transmitter as set forth in claim 12, in which a spring roller isprovided on one end of said main shaft, which spring roller bears on anabutting segment fastened on said locking shaft in order to fix thelocking shaft in position.

14-. A transmitter as set forth in claim 13, in which the locking shaftends in a slot which acts as a keyhole for a key for turning the lockingshaft.

15. A transmitter as set forth in claim 14, in which the keyhole iscovered by a gravity-biased plate, so that the key with its stopping pincan be inserted only when the apparatus is in a specific position.

References Cited in the file of this patent UNITED STATES PATENTS2,386,486 Mallina Oct. 9, 1945

1. PULSE TRANSMITTER FOR TELEPHONES COMPRISING: AT LEAST TWO ROTATABLECAMS; A FOLLOWER MEMBER FOR EACH OF SAID CAMS, NORMALLY KEPT OUT OF THERANGE OF ITS RESPECTIVE ASSOCIATED CAM; A COMMON LOCKING PAWL ACTUATEDBY SAID FOLLOWER MEMBERS IN SYNCHRONIS WITH CAM ACTION THEREUPON; A KEYASSOCIATED WITH EACH OF SAID FOLLOWER MEMBERS FOR SELECTIVELY PLACINGSUCH ASSOCIATED FOLLOWER MEMBER IN THE ACTUATING RANGES OF ITSASSOCIATED CAM AND OF SAID LOCKING PAWL; MEANS ACTUATED IN SYNCHRONISMWITH SELECTION OF A FOLLOWER MEMBER FOR RETAINING SAID FOLLOWER MEMBERAFTER SELECTION THEREOF IN SAID ACTUATING RANGES OF SAID CAM AND OF SAIDLOCKING PAWL; MEANS ACTUATED IN SYNCHRONISM WITH SAID CAMS FOR REMOVINGSAID SELECTED FOLLOWER MEMBER FROM SAID ACTUATING RANGES; A ROTATABLEPULSE WHEEL; A FIRST CONTACT ACTUATED BY SAID PULSE WHEEL; A ROTATABLELOCKING WHEEL; A SECOND CONTACT ACTUATED BY SAID LOCKING WHEEL; DRIVINGMEANS; AND MEANS OPERATED BY SAID LOCKING WHEEL FOR SIMULTANEOUSLYCONNECTING SAID LOCKING WHEEL AND SAID PULSE WHEEL TO SAID DRIVINGMEANS.